Hi FrankieI have the same problem. I just cut a piece of asbestos rope the width of the flame guide and pressed it in so the rope was tight. It held the flame guide from moving. My guide was moving ever so slight when pellets were fed. The pellets were actually making the guide move and allowing the same fire that you have. Try a strip of 1/2 or 3/4 inch rope and see what happens. I cut the rope in 3 inch lengths.
Can you be a little more specific about where you put the rope behind the flame guide ?
Across the top of it or across the bottom or both ?
Yes the flame guide does move ever so slightly So this is definitely worth a try .
I just ran out and got the gasket rope but don't want to put it in until I am sure how you want it...
Thanks ever so much